Two-stone corner squeeze

    Keywords: Tesuji, Tactics

Chinese 1: 大头鬼 (d tu guǐ, big-headed ghost)
Chinese 2: 秤砣 (chng tu, steelyard weight)
Chinese 3: 拔钉子 (b dīng zi, pulling nails)
Japanese: 石塔シボリ (sekito shibori)
Korean: -

The two stone corner squeeze is a technique used in capturing races in the corner. It is a corner variation of the two-stone edge squeeze (aka "stone pagoda squeeze").

Table of contents

Example

[Diagram]
White to play  

White wants to find a way to capture the marked black stones. Given the fact that both the black and the white stones have three liberties, white should find a sequence that never allows the black stones to develop more than three liberties. The two stone corner squeeze satisfies that criterion. Let's see how it is used here.


Solution

[Diagram]
Race to capture  
[Diagram]
Continuation  
[Diagram]
Finish  

W1 and W3 initiate the race to capture.

If Black connects at a after W13, both groups have three liberties with White to move. And although the black group has an eye, there are no shared liberties, so it does not help.

If black fills an outside liberty instead, then the atari at a wins.

White won the race to capture with the two stone corner squeeze, because of the special properties of the corner.

Failure

[Diagram]
Wrong squeeze  
[Diagram]
Continuation  
[Diagram]
Failure  

It is tempting to play the more obvious squeeze with W5 and W7, but it is wrong, again given the special properties of the corner.

This is one possible continuation. It is race between a group with an eye and one without again, but this time there is a shared liberty. Black has one exclusive liberty in the eye (circle where B18 captured) and counts the internal liberty at a as well as the approach liberties b and c. That's four liberties. White counts the circled liberties and has three. White loses the semeai.

Joseki

[Diagram]
Joseki  
[Diagram]
Possible line  
[Diagram]
B27 @ B21, W28 @ white+circle  

In response to the high approach white+circle, the two space high pincer of B1 is a popular move. W2 is one of the usual replies, B3 is less usual. W4 through W10 is one possible line of play. After W12, B13 initiates the two stone corner squeeze.

White has no choice but to sacrifice three stones, escaping with W24. After W28, black is left with bad shape, and white is not unsatisfied.

Common position

[Diagram]
Joseki result  

The position in the corner is the result of a very common joseki. When White plays the peep W1, usually black defends at a.

Suppose, however, that black decides not to defend. Black might, for example, wish to develop the upper side with B2. white pushes through and cuts with W5. Black has two options: defend at a or capture at b. We will look at both options.

[Diagram]
Defend  

If black defends with B6, W7 cuts off the two stones in the center, and black is on the run. Unless black has closeby support along the top, this does not bode well for black.

[Diagram]
Capture  

When black captures with B6, white cuts and extends with W7 and W9. Things are looking bleak for black's corner stones. The question is: How to continue with black.

[Diagram]
Nose hit  

The tesuji that black is looking for is B1. After the hane and cut W2-B3, black can play the two stone corner squeeze.

[Diagram]
B15 @ B9  

Up to B15, black manages to rescue his corner stones. His corner territory is devastated however,so the importance of black+circle should be quite large before black chooses to ignore the peep.


Two-stone corner squeeze last edited by 50.139.64.243 on August 5, 2013 - 01:17
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